Electrophysiological detection of electrode fold-over in perimodiolar cochlear implant electrode arrays: a multi-center study case series

Mittmann, Philipp; Lauer, G; Ernst, Arne; Mutze, Sven; Hassepaß, Frederike; Arndt, Susan; Arweiler‐Harbeck, Diana; Christov, Florian

doi:10.1007/s00405-019-05653-9

Cited by 17 publications

(22 citation statements)

References 28 publications

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“…It is possible but very difficult to detect undesired array positions including TF in the use of peri-modiolar electrode arrays (51), as well as translocation or kinking into the scala vestibuli (52,53) using NRT and impedance. However, cases of malposition have also been missed with reported normal intraoperative readings (14,54,55). In-keeping with this, within our own series of malpositions (Table 3), impedances are often normal, and ECAP may be present or absent on affected electrodes.…”

Section: Nrt and Impedancessupporting

confidence: 72%

“…Postoperative X-ray is considered the gold standard to check the position of the electrode array, as TF can be detected easily with this imaging modality. Whereas TF classically displays normal intraoperative telemetry measurements (14,16), transimpedance matrix (TIM) can reliably detect TF as found in recent studies (17). Suboptimal placement of the array in the form of TF or kinking, although not ideal, may be successfully managed with deactivation of affected electrodes during mapping if needed (18,19).…”

mentioning

confidence: 97%

“…The rate has been reported as occurring in approximately 2% in some series, with a higher incidence reported in the presence of cochlear abnormalities (10). Tip foldover has been well reported in the literature, with individual centres reporting their experiences with perimodiolar devices (13)(14)(15) and is reported to occur more frequently with perimodiolar electrodes compared with lateral wall electrode array designs (10,11). Postoperative X-ray is considered the gold standard to check the position of the electrode array, as TF can be detected easily with this imaging modality.…”

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confidence: 99%

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Misplaced Cochlear Implant Electrodes Outside the Cochlea: A Literature Review and Presentation of Radiological and Electrophysiological Findings

Cheung

Kong

Chu

et al. 2022

Otology &Amp; Neurotology

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Hypothesis:It is possible to detect when misplacement and malposition of the cochlear implant (CI) electrode array has occurred intraoperatively through different investigations. We aim to explore the literature surrounding cochlear implant misplacements and share our personal experience with such cases to formulate a quick-reference guide that may be able to help cochlear implant teams detect misplacements early.Background:Misplacement and malposition of a cochlear implant array can lead to poor hearing outcomes. Where misplacements go undetected during the primary surgery, patients may undergo further surgery to replace the implant array into the correct intracochlear position.Methods:Systematic literature review on cochlear implant misplacements and malpositions and a retrospective review of our program's cases in over 6,000 CI procedures.Results:Twenty-nine cases of CI misplacements are reported in the English literature. Sixteen cases of cochlear implant misplacements are reported from our institution with a rate of 0.28%. A further 12 cases of intracochlear malpositions are presented. The electrophysiological (CI electrically evoked auditory brainstem response, transimpedance matrix) and radiological (X-ray and computed tomography scan) findings from our experience are displayed in a tabulated quick-reference guide to show the possible characteristics of misplaced and malpositioned cochlear implant electrode arrays.Conclusion:Both intraoperative electrophysiological and radiological tests can show when the array has been misplaced or if there is an intracochlear malposition, to prompt timely intra-operative reinsertion to yield better outcomes for patients.

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Section: Nrt and Impedancessupporting

confidence: 72%

mentioning

confidence: 97%

mentioning

confidence: 99%

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Misplaced Cochlear Implant Electrodes Outside the Cochlea: A Literature Review and Presentation of Radiological and Electrophysiological Findings

Cheung

Kong

Chu

et al. 2022

Otology &Amp; Neurotology

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“…Other electrophysiological methods of deriving the electrode array position have been tried [Müller et al, 2021]. Neural response telemetry is one viable option but measuring the threshold of the evoked compound action potential was not found to be a reliable tool for detecting TFOs [Zuniga et al, 2017;Mittmann et al, 2020]. Using neural response telemetry to measure the spread of excitation, however, has produced some encouraging results [Grolman et al, 2009;Cosetti et al, 2012].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a Transimpedance Matrix Algorithm to Detect Anomalous Cochlear Implant Electrode Position

Hoppe¹,

Brademann²,

Stöver³

et al. 2022

Audiol Neurotol

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Introduction: Transimpedance measurements from cochlear implant electrodes have the potential to identify anomalous electrode array placement, such as tip fold-over (TFO) or fold-back, basal electrode kinking, or buckling. Analysing transimpedance may thus replace intraoperative or post-operative radiological imaging to detect any potential misplacements. A transimpedance algorithm was previously developed to detect deviations from a normal electrode position with the aim of intraoperatively detecting TFO. The algorithm had been calibrated on 35 forced, tip folded electrode arrays in six temporal bones to determine the threshold criterion required to achieve a sensitivity of 100%. Our primary objective here was to estimate the specificity of this TFO algorithm in patients, in a prospective study, for a series of electrode arrays shown to be normally inserted by post-operative imaging. Methods: Intracochlear voltages were intraoperatively recorded for 157 ears, using Cochlear’s Custom Sound™ EP 5 electrophysiological software (Cochlear Ltd., Sydney, NSW, Australia), for both Nucleus® CI512 and CI532 electrode arrays. The algorithm analysed the recorded 22 × 22 transimpedance matrix (TIM) and results were displayed as a heatmap intraoperatively, only visible to the technician in the operating theatre. After all clinical data were collected, the algorithm was evaluated on the bench. The algorithm measures the transimpedance gradients and corresponding phase angles (θ) throughout the TIM and calculates the gradient phase range. If this was greater than the predetermined threshold, the algorithm classified the electrode array insertion as having a TFO. Results: Five ears had no intraoperative TIM and four anomalous matrices were identified from heatmaps and removed from the specificity analysis. Using the 148 remaining data sets (n = 103 CI532 and n = 45 CI512), the algorithm had an average specificity of 98.6% (95.80%–99.75%). Conclusion: The algorithm was found to be an effective screening tool for the identification of TFOs. Its specificity was within acceptable levels and resulted in a positive predictive value of 76%, with an estimated incidence of fold-over of 4% in perimodiolar arrays. This would mean 3 out of 4 cases flagged as a fold-over would be correctly identified by the algorithm, with the other being a false positive. The measurements were applied easily in theatre allowing it to be used as a routine clinical tool for confirming correct electrode placement.

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“…This has been reported at a rate of 1.57% and electrode scalar deviation at 22.38% [7]. Characteristic intraoperative electrophysiological changes to predict tip fold-over have been described [5] but are often absent in radiologically confirmed cases [4,8]. Kinking also occurs when the electrode is advanced against resistance causing the electrode to curl upon itself and can occur at any point in the length of the electrode.…”

Section: Discussionmentioning

confidence: 99%

The Modified Stenver’s View for Cochlear Implants – What do the Surgeons Want to Know?

McClenaghan

Nash

2020

Journal of the Belgian Society of Radiology

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Electrophysiological detection of electrode fold-over in perimodiolar cochlear implant electrode arrays: a multi-center study case series

Cited by 17 publications

References 28 publications

Misplaced Cochlear Implant Electrodes Outside the Cochlea: A Literature Review and Presentation of Radiological and Electrophysiological Findings

Misplaced Cochlear Implant Electrodes Outside the Cochlea: A Literature Review and Presentation of Radiological and Electrophysiological Findings

Evaluation of a Transimpedance Matrix Algorithm to Detect Anomalous Cochlear Implant Electrode Position

The Modified Stenver’s View for Cochlear Implants – What do the Surgeons Want to Know?

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